Fluids such as water, oil, and the like are often "conditioned" by filtering the fluid to remove particulate matter. Typically, a filter housing supports a filter cartridge through which the fluid passes. The cartridge usually incorporates one or more filter membranes through which the fluid passes to remove the particulate. A typical construction for a filter cartridge comprises a core element which is adapted to support the filter membrane without obstructing the flow of fluid through the cartridge.
One common application of such fluid filter cartridges is in pool filter systems. In this such application, it is important to remove particulate contaminants in the water in order to keep the pool clean and to protect the mechanical elements of the pool system such as the heater and pump. A typical pool filter cartridge and filter housing are seen in U.S. Pat. No. 5,190,651 to Spencer et al. This filter system is formed from a quasi-cylindrical or egg-shaped filter housing and a cylindrical filter cartridge received therein. Although not expressly described in the Spencer patent, the cylindrical core of the filter cartridge is assembled from two, identical, hemicylindrical rigid core halves. The core halves incorporate interacting tabs and slots so that the rigid core halves can be snap-fit together to create a complete cylindrical filter core. A filter membrane is mounted on both the inside and outside of the filter core and held in place by upper and lower end caps. Generally, fluid passes through either the inner or outer membrane into the annular space defined by the filter core. The filtered water then flows through the interior of the filter cartridge for ultimate discharge from the filter housing.
The filter cartridge assembly as seen in the Spencer patent is effective for filtering the fluid. However, not unlike many manufactured articles, it can be manufactured more cost-effectively. First, the hemicylindrical rigid core halves are expensive to mold in that the costs for the detailed, hemicylindrical mold dies are extremely costly. This is due primarily to the depth of the hemicylindrical body and the detail of the resulting molded article. In addition, different mold halves must be formed for each particular size of the filter cartridge. In other words, for twenty-five and twenty-nine inch diameter filter cartridges filter housings will require two different sets of molds. While these filter cartridges are effective for filtering fluid, experimentation has shown that they can be relatively costly to manufacture as compared to invention.